1. Field of the Invention
The present invention relates to cursive writing type word processing systems and particularly to a system that provides for increasing the size of the characters on a display and for changing the pitch of a line of characters.
2. Description of the Prior Art
Electronic word processing systems commonly utilize a keyboard and magnetic tape and card reader inputs. A cathode ray tube screen is generally provided with characters entered into the system appearing on the screen. The characters are generated in some systems digitally utilizing a matrix of dots or the like. Such characters are often difficult to read because of their discontinuous nature. Therefore, another type of character display is utilized in the cursive writing type word processing systems. Here the electron beam of the cathode ray tube is scanned to form a raster with one raster line for each character line. Typically, magnetic deflection circuits are utilized to produce the scanning raster. The beam may then be deflected by an electrostatic deflection system so as to cause characters to be written on the screen as sequences of short continuous lines. While the operation and control of such systems may be through well known digital processing techniques, digitally coded characters will have their information converted to analog signals to drive the deflection system. Similarly, analog signals are applied to the brightness control electrodes of the cathode ray tube to permit blanking of the screen when necessary and to vary the brightness of individual strokes of the cursive letters to maintain even brightness of each character. An example of a cursive character generator may be found in U.S. Pat. No. 4,205,309 to Music and assigned to Documation Incorporated.
Many users consider that the cursive written characters are more easily read than digitally generated characters. However, in any case, the ease of reading is a function of the size of the cathode ray display screen. For cost and convenience reasons, relatively small size screens are highly desirable. Particularly with small screens, a full type written page with, for example, 64 lines, results in relatively small characters. It is therefore desirable to be able to selectively expand the character sizes to improve readability and to minimize eyestrain on the part of the operator when editing and reviewing information in the system. When using a purely digital character generation method, expansion is easily accomplished simply by changing the gain in the deflection circuits. However, in the cursive writing systems, changes in the scanning deflection circuits will result in an increase in writing rate necessary, and will therefore require correction in the brightness of individual strokes and other compensation inherent in the digital to analog conversion circuits necessarily used.